GitHub Action for flamegraphs on PR as comment

flamegraph-pr.yml

name: Flamegraph PR
on:
  pull_request:
  workflow_dispatch:

concurrency:
  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
  cancel-in-progress: true

jobs:
  flamegraph:
    if: contains(github.event.pull_request.labels.*.name, 'flamegraph')
    name: flamegraph
    runs-on: ubuntu-latest
    timeout-minutes: 8

    steps:
      - uses: actions/checkout@v4
      - name: determine the new added project
        id: determine_project
        run: |
          # Get the name of the main branch (assuming it's 'main')
          MAIN_BRANCH="main"

          # Fetch the main branch
          git fetch origin $MAIN_BRANCH:$MAIN_BRANCH

          NEW_FOLDER=$(git diff --name-status $MAIN_BRANCH | grep -E '^[AM]' | awk '{print $2}' | grep 'Cargo.toml' | awk -F/ '{printf("%s/%s\n", $1, $2)}' | uniq)

          # Extract the names of new folders
          if [[ -z "$NEW_FOLDER" ]]; then
            echo "No new project found - skipping the build"
            gh run cancel ${{ github.run_id }}
            gh run watch ${{ github.run_id }}
          fi

          # Set the output variable
          echo "PROJECT_FOLDER=$NEW_FOLDER" >> "$GITHUB_OUTPUT"
        env:
          GH_TOKEN: ${{ github.token }}
      - name: setup | rust
        uses: dtolnay/rust-toolchain@stable
        with:
          default: true
          profile: minimal
      - name: build
        run: cargo build --release
        working-directory: ${{ steps.determine_project.outputs.PROJECT_FOLDER }}

      - name: install flamegraph
        run: cargo install flamegraph

      - name: generate flamegraph
        run: |
          cargo flamegraph --root --verbose --cmd "record -F 997 --call-graph dwarf,16384 -g -o /tmp/perf.data" -- ../../samples/weather_1M.csv
        shell: bash
        working-directory: ${{ steps.determine_project.outputs.PROJECT_FOLDER }}
        env:
          CARGO_PROFILE_RELEASE_DEBUG: "true"

      - name: rename the flamegraph to gitsha and run.id
        run: |
          mkdir -p guide/book/_flamegraphs
          mv ${{ steps.determine_project.outputs.PROJECT_FOLDER }}/flamegraph.svg guide/book/_flamegraphs/flamegraph-${{ github.sha }}-${{ github.run_id }}.svg
        shell: bash

      - name: Store flamegraph
        uses: peaceiris/actions-gh-pages@v4
        with:
          github_token: ${{ secrets.GITHUB_TOKEN }}
          publish_dir: guide/book
          keep_files: true

      - name: post comment
        run: |
          # link of the just uploaded artefact
          # TODO: replace the things in the URL below with your stuff
          LINK='https://<your-org-or-gh-handle>.github.io/<repo-name>/_flamegraphs/flamegraph-${{ github.sha }}-${{ github.run_id }}.svg'

          GITSHA=$(git rev-parse HEAD)

          echo "### Flamegraph at $GITSHA" > comment.md
          echo "" >> comment.md
          echo "![flamegraph]($LINK)" >> comment.md
          echo "" >> comment.md

          # Post the comment to the PR
          gh pr comment ${{ github.event.pull_request.number }} -F comment.md
        env:
          GH_TOKEN: ${{ github.token }}